类别 全部 - tenses - laws - obligation - advice

作者:MARÍA JOSEFA MARTÍN MOYANO 8 月以前

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MODAL VERBS OF OBLIGATION

Modal verbs are essential in English to express different forms of obligation and advice. "Have to" is used to indicate rules or laws imposed by external factors and applies to all tenses.

MODAL VERBS OF OBLIGATION

MODAL VERBS OF OBLIGATION

SHOULD/SHOULDN'T

ADVICE
We shouldn't stay up until late
We should leave early

HAVE TO

Rules, laws, coming from OUTSIDE
All tenses
Do-Does for questions
-s in the 3rd person singular

MUST

PERSONAL obligation
You MUST see the doctor
only present form
followed by infinitive without to

Ex. I MUST do my homework